Generally, automotive doors for motor vehicles comprise a structural inner door panel, an outer panel, trim surfaces, and associated hardware, e.g., latches, window glass, regulators, switches, and speakers. The inner door panel provides structural support and mounting surfaces for the hardware. The outer panel attaches to the inner door panel to provide an aesthetic outside surface, as well as increase the rigidity of the entire door structure. The trim surfaces provide an aesthetic inside covering to the inner door panel as well as some functional features, e.g., pull cups and ashtrays.
Inner door panels are typically manufactured from various metal forming operations, e.g., stamping, roll forming, or welding. The header of the inner door panel provides the frame into which the visible window glass fits and extends upwardly from the lower boundary of the visible window glass, i.e., from the beltline. The header may be manufactured as an integral part of the door assembly comprised of a stamped metal inner panel hem bonded to a stamped metal outer panel, or as a separate piece which is joined to the lower section of the inner door panel at just below the beltline.
During production line assembly of automotive vehicles, the inner door panels must be rapidly mounted within door openings of the vehicles via hinges, e.g., one per minute. However, the dimensions of the door openings will vary due to the stacked up tolerances of the many different operations required to assemble the vehicle. Additionally, door inner panel dimensions also vary due to assembly tolerance stacking as well as paint related operations. As a result the inner door panels must be rapidly adjusted to fit each individual door opening on the assembly line.
This adjustment process is time consuming, labor intensive and imprecise. If the inner door panel must be adjusted toward the vehicle (inboard) to fit the door opening, substantial pressure is manually applied at the top of the header to force the inner door panel to bend slightly at approximately the beltline. The fit is then checked, and the adjustment process is repeated until a proper fit has been obtained. If the inner door panel must be bent away from the vehicle (outboard), the adjustment process is even more difficult.
Because of the crude nature of the above described adjustment process, modular doors cannot be mounted to the door openings of a vehicle on an assembly line without incurring a risk of damage. Therefore, inner door panels are typically mounted and adjusted first, and the other components of the automotive door are assembled further down the assembly line. This increases the amount of parts that must be stocked on the assembly line, consequently increasing the overall time and cost of manufacture of the vehicle. This also inhibits the ability to consolidate parts, and to supply a fully assembled, pre-tested modular door to an original equipment manufacturer (OEM).
Modular doors that consist of an inner door panel alternatively manufactured from a polymeric, e.g., thermoplastic, molding process are generally more precisely formed than metal inner door panels. However, the polymeric inner door panels are not adjustable. That is, the polymeric material will either snap back to its original shape, or crack, if bent to fit a door opening. As a result, the metal inner door panels are preferred over the polymeric inner door panels in spite of the fact that the metal inner door panels are difficult to adjust.
A number of the above referenced components can be pre-assembled and/or consolidated to form a modular door, which are generally pre-tested for functionality and inspected prior to assembly to the vehicle. Modular doors can range in complexity from an inner door panel with a few hardware components attached, to a fully assembled automotive door. In producing a modular door, there are parts consolidation benefits resulting in cost and weight reduction to be gained by molding the door inner panel (with associated function and trim) from polymeric materials.